<?php
/**
 * Smarty plugin
 * @package Smarty
 * @subpackage plugins
 */


/**
 * Smarty {math} function plugin
 *
 * Type:     function<br>
 * Name:     math<br>
 * Purpose:  handle math computations in template<br>
 * @link http://smarty.php.net/manual/en/language.function.math.php {math}
 *          (Smarty online manual)
 * @author   Monte Ohrt <monte at ohrt dot com>
 * @param array
 * @param Smarty
 * @return string
 */
function smarty_function_math($params, &$smarty) {
// be sure equation parameter is present
  if (empty($params['equation'])) {
    $smarty->trigger_error("math: missing equation parameter");
    return;
  }

  // strip out backticks, not necessary for math
  $equation = str_replace('`','',$params['equation']);

  // make sure parenthesis are balanced
  if (substr_count($equation,"(") != substr_count($equation,")")) {
    $smarty->trigger_error("math: unbalanced parenthesis");
    return;
  }

  // match all vars in equation, make sure all are passed
  preg_match_all("!(?:0x[a-fA-F0-9]+)|([a-zA-Z][a-zA-Z0-9_]+)!",$equation, $match);
  $allowed_funcs = array('int','abs','ceil','cos','exp','floor','log','log10',
      'max','min','pi','pow','rand','round','sin','sqrt','srand','tan');

  foreach($match[1] as $curr_var) {
    if ($curr_var && !in_array($curr_var, array_keys($params)) && !in_array($curr_var, $allowed_funcs)) {
      $smarty->trigger_error("math: function call $curr_var not allowed");
      return;
    }
  }

  foreach($params as $key => $val) {
    if ($key != "equation" && $key != "format" && $key != "assign") {
    // make sure value is not empty
      if (strlen($val)==0) {
        $smarty->trigger_error("math: parameter $key is empty");
        return;
      }
      if (!is_numeric($val)) {
        $smarty->trigger_error("math: parameter $key: is not numeric");
        return;
      }
      $equation = preg_replace("/\b$key\b/", " \$params['$key'] ", $equation);
    }
  }

  eval("\$smarty_math_result = ".$equation.";");

  if (empty($params['format'])) {
    if (empty($params['assign'])) {
      return $smarty_math_result;
    } else {
      $smarty->assign($params['assign'],$smarty_math_result);
    }
  } else {
    if (empty($params['assign'])) {
      printf($params['format'],$smarty_math_result);
    } else {
      $smarty->assign($params['assign'],sprintf($params['format'],$smarty_math_result));
    }
  }
}

/* vim: set expandtab: */

?>
